Can you tell us a little more about your device? Model Number & Android Version.

Things we need to know:

1 Did you recently upgrade to a newer Android Version?
2.Did you recently install an app, that might have caused this issue?
3 Did you drop or by other means, cause damage to your phone? Drops may not show external damage, but could cause internal damage.
3.Did you get it wet?

1 thing to try immediately: Enter recovery and do a Wipe of the Cache Partition